Method for rapidly painting metal sheets



MarchZZ, 1949. H. J. LITTLE METHOD FOR RAPIDLY PAINTING METAL SHEETS Filed Jan. 24, 1949 INVENTOR. Howmo wLLrrna AT TORN EN Patented Mar. 22, 1949 METHOD FOR RAPIDLY PAINTING METAL SHEETS Howard J. Little, Fort Thomas, Ky.

Application January 24, 1949, Serial No. 72,364

2 Claims.

This invention relates to a method for rapidly coating sheets with paints, varnishes, lacquers and similar fluid or semi-fluid solvent containing materials which dry and set to a hardened condition after being applied in relatively thin layers or films to the surface of the sheets. The coating material is applied to the surface of the sheets by any suitable means, heated to drive ofi the solvents and then quickly cooled substantially to its final set and cured to a hardened condition so that the coated products are immediately ready for stacking, packing or recoating when discharged from the coating machine without requiring further drying preliminary to packing,

stacking or recoating. Accordingly, handling of and packaging the coated products is expedited, and all special handling for drying is eliminated as is the large storage space which is ordinarily required for drying and the special stacking incident to drying.

An object of my invention is to provide a method for rapidly painting and drying metal sheets.

:Another object is to provide a method for quickly drying the painted metal sheets so that they are ready for handling upon being discharged from the painting machine.

While, as stated above, any suitable means may be employed for applying the paint material to the surface of the sheets, the invention aims to mechanically apply this as a unit of the same machine which dries and quickly cools the paint material after same is applied to the sheets.

The invention, while particularly adapted for painting fiat metal sheets or strips, may be employed for other painted products which are made in large volume and are to be immediately packed without being specially handled for drying.

After the sheets are painted with a film of paint material, the painted sheets are heated from about 600 F. to 1000 F. to evaporate the solvents from the paint material, and then they are quickly cooled to about 100 F. or below. The solvent of some of the more highly volatile and quicker drying paints can be driven off by heating the painted sheets within a lower range down to 400 F. Water may be used advantageously for quickly cooling the sheets. The elevated temperature of the painted sheets, either with or without the assistance of a blast of air, is sufiicient to dry off the moisture when the water is applied in properly regulated quantities.

This case is a continuation-in-part of my application Serial No. 586,542 filed April 4, 1945, now abandoned.

For a better understanding of the invention, reference may be made to the accompanying drawings, in which:

Fig. 1 is a side elevation of a painting, heating and cooling machine embodying the invention; and

Fig. 2 is a side elevation of a portion of a modified form of the machine.

Referring specifically to the drawings in which like numerals are used to designate like parts, the machine comprises three units which may be generally referred to as the paint applicator i, drying device 2, and the cooling means 33, disposed in sequence for having fed. therethrough the sheets which are to be painted. This series of units may be duplicated if it be desirable to apply a second or a plurality of paint coatings upon the sheets. Or additional painting material may be applied to the sheets by refeeding them through the series of units, and they may be refed to apply as many paint coatings as are desired.

The coating applicator comprises upper and lower paint transfer rolls 4 and 5 with the lower roll 5 immersed in a bath of paint material which is contained in trough 6 and is distributed over' the periphery of the roll. Paint material is also distributed over the periphery of roll 4 inasmuch as roll 4 is in rolling contact with roll 5 when the sheets are not therebetween. Thus, adequate painting material is distributed upon the periphery of roll 4 from roll 5 at those intervals when the sheets are not in contact with the rolls if the sheets being painted are less in length than the periphery or circumference of the roll 4. If the sheets being painted are longer than the periphery or circumference of roll 4, the paint material may be applied to the surface of roll 4 by any mechanical device.

The drying unit 2 comprises an endless conveyor l which is threaded over a series of rolls or sprockets 8 in position to receive the painted sheets as they are discharged from the applicator unit. The conveyor may be of any material but is preferably chains, wire screening or similar devices which give minimum contact points between the conveyor and the sheets. Sheets 9 are fed between the coating applicator rolls which apply paint material to one or both faces of the sheets. The sheets are then discharged on the conveyor which traverses them along, in the direction of the arrow, through the heating chamber or chambers l0. Heat to the heating chambers may be supplied by any suitable heating means, such as gas, oil or electric burners or bulbs. The

The temperature to which paintedfrf only about 400 F. or higher, whereasithose paints with less volatile solvents need to be heated to 1 higher temperatures Within the range. The heated painted sheets are too hot to beconveniently handled, and the paint materialisknot h'ard even though substantially all of the solvents may have been driven from it. Quick cooling of the paint ed sheets to a near normal or room temperature improves the paint material and conditions the treated sheets so that they can be immediately handled, packaged, stacked or repainted.-

Various means 'may' be employed for quickly cooling the sheets, but water coolin means-is preferable. This may be effected by subjecting the painted and heated-sheets to-a water bath-by means of any suitable apparatus for water quenching. Rolls l2 and I3, similar to coating rolls 4 and 5, may be employed. The bottom roll I3 is partly immersed-in water contained within trough l4. As the painted and heated sheets are fed between" rolls [2 and [3- in being discharged from the .end of the conveyor,.water will heapplied to the two sides of the sheets bythe rolls. Theperiphery of roll 12 is covered with a water film supplied from roll [3 at intervals when the" sheets are not in contact with the rolls, or'water may be mechanically supplied to the roll l2 in any other devised manner. From the cooling rolls;-: the painted sheets pass to a take-01f. conveyor 5 1 for being conveyed to any place for being stacked or packaged.

One set of cooling rolls. is ordinarily-sufii'cient,; but any number of sets may be used aloneorsin: combination with other cooling means. The. painted sheets are sufiiciently warm to drythe moisture from them by thetime that theynare ready to be removed fromthe conveyor [5.1: To

expedite and insure drying the moisture from the painted sheets or for cooling them in conjunction with the water cooling means, air may be blown through jets l6 against the opposite surfaces of the painted sheets. As a result, the sheets are not only cooled to substantially normal or room temperature but they are completely dry and the paint cured ready for packing when taken off the conveyor.

Fig.- 2 shows a modification of the cooling means. In lieu of the water cooling rolls, a chamber 11 may be provided into which a cooling; vapor may be: fed through conduit l8. This cooling vapor means may not only be used alone in place of the water cooling means but in combination with it. Exhaust pipe I I is connected to theatoppf the chamber I! to return the cooling means for recirculation. One or more rollers l8 maybe provided for supporting the sheets 9 as they pass from conveyor-1 to conveyor 15.

Itwill be: understood that the time during which-the painted sheets are subjected to the heatin or dryingmeans' and also to the cooling means :may be regulated by the speed with which they are .fed through. the apparatus.

Having described the invention, I claim: 1. A. method for rapidly painting metalsheett comprisingv applying. a. solvent-containing paint 1 toathensurface ofthe: sheets, heating :the metald sheets. fromabout1600 F; to 1000 F; to evaporate thesoltventfrom the: paint, applying. .water toithe hot-unset painted sheets. for quickly coolingsame. to-about F; temperature,: thereby setting the. paint,'and-drying the; retained waterv from the sheetsv with the residualheat. from the heated:

2.. A method for rapidly painting. metal: sheets i the-solvent from-the paint, applyin water to .the

hot unset painted-sheets for quickly cooling same:

to about 100 F. temperaturethereby. setting the paint, and drying the retainedwater from. the: sheets with the residual heat .from theheated.

sheets.

HOWARDJ. LITTLE;

No references cited. 

